1. Field of the Invention
The present invention relates-to-a semiconductor light-emitting element which produces light by the recombination of a carrier in a semiconductor and a method of manufacturing the same, and more particularly to a semiconductor light-emitting element suitable for blue light emission and a method of manufacturing the same.
2. Description of the Related Art
A blue (bluish purple) semiconductor light-emitting element, for example, a 400-nm band semiconductor laser element, adopts a structure having a p-type carrier overflow prevention layer between an active layer and a p-side light guide layer to effectively confine a carrier. Such a structure is disclosed in, for example, Japanese Patent Laid-Open Applications No. 2000-299497 and No. HEI 11-340580. According to the former literature, a p-type electron confining layer corresponding to the p-type carrier overflow prevention layer is formed by growing a crystal by raw material gas containing gas having an impurity. And, a light guide layer (p side) is formed on the formed electron confining layer by undoping, and the light guide layer is rendered to be a p-type semiconductor by diffusion of the impurity from the electron confining layer. The impurity concentration is inevitably small to 5×1015 cm−3 because of a process of diffusion.
The latter literature discloses that the impurity (magnesium) concentration in an electron block layer corresponding to the p-type carrier overflow prevention layer in a similar structure is determined to be 7×1019 cm−3 or more.                [Patent Document 1]        Japanese Patent Laid-Open Application No. 2000-299497 (FIG. 5, paragraphs 0041, 0042)        [Patent Document 2]        Japanese Patent Laid-Open Application No. HEI 11-340580        
The p-type carrier overflow prevention layer provides an effect of effectively confining electrons, which are supplied from the n side, on the active-layer because the band gap is large. But, it is also necessary to consider an influence of the disposed p-type carrier overflow prevention layer on the carrier supplied from the p side. This fact was found by the present inventors by making a study. Especially, the impurity concentrations in the p-type carrier overflow prevention layer and the p-side light guide layer become a problem. Depending on the values of the impurity concentrations, they become a barrier against the carrier supplied from the p side in the process of reaching the active layer and prevent the carrier from recombining in the active layer, resulting in degradation of properties that the operating voltage is increased, the light emission efficiency is degraded, and the like.